Visible light activated photocatalysts can be deployed for self-cleaning, air and water purification and many other interesting applications usually without any post-deployment, non-renewable energy costs. This is because the photocatalysts are able to decompose pollutants (like dyes, volatile organic compounds and NOx) using ambient light like solar radiation or indoor and outdoor lighting. With the anticipated rapid adoption of UV-free indoor lighting (like LEDs and OLEDs), it would be helpful to find ways to deploy visible-light activated photocatalysts in indoor applications, for instance, in cleaning room air in domestic, public and commercial spaces, especially in confined areas like aircraft, public buildings, etc. Moreover, additional applications for antibacterial surfaces and self-cleaning materials can have wide applicability in the food service, transportation, health care, and hospitality sectors.
Elemental copper, copper composites, alone or in combination with metal oxides, may be useful as photocatalytic/antibacterial/antiviral materials. Elemental copper, however, shows a degradation of antibacterial activity over time (durability) and unappealing cosmetic appearance change (from copper (Cu) metal to black copper oxide (CuO)), both believed due to oxidation of elemental copper under normal application conditions. Thus, there is a need for improved longevity of antibacterial activity over time. Thus, there is a need for photocatalytic materials that provide antibacterial/antiviral activity without unappealing cosmetic appearance changes.
The current disclosure describes heterogeneous materials having a p-type semiconductor comprising mixed valence oxide compounds and an n-type semiconductor having a deeper valence band than that of the p-type semiconductor, wherein the semiconductors are in ionic charge communication with each other. These multivalent heterogeneous materials can be used to enhance the photocatalytic activity of photocatalytic materials and to improve durability (i.e., maintain photocatalytic activity over time). Photocatalytic materials are useful for having and/or enhancing antibacterial (light and dark) activity, antiviral activity, decomposition of volatile organic compounds (VOC), and/or dye discoloration in aqueous solutions.